As information and communication technologies evolve, it becomes easier to enjoy multimedia content on multimedia service platforms via the web. Interactions between entities on social multimedia service platforms such as YouTube and Facebook “Watch” are different from those on platforms that have been used earlier. A user who exploits the multimedia service platforms can not only consume multimedia content, but also act as a multimedia generator by producing or uploading multimedia content. In the situation, multimedia content that has not been properly validated can be supplied and consumed indiscriminately. Under this circumstance, utilizing the concept of trust can be a good solution to establish a healthy multimedia service environment. In this paper, we suggest considerable trust relationships in a multimedia service environment. For each trust relationship, we propose sets of influential trust factors that can be inferred from data and metadata. To show the possibility of measurement for the influential trust factors, we describe how the data and metadata can be exploited.